John w



UNITED STATES PATENT OFFICE.

JOHN W. MURPHY, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO A. AND P.ROBERTS, OF SAME PLACE.

IRON TRUSS-GIRDER.

Speccation of Letters Patent No. 28,240, dated May 8, 1860.

To all whom it may concern:

Be it known that I, JOHN W. MURPHY, of t-he city and county ofPhiladelphia and State of Pennsylvania, have invented a new and usefulImprovement in the Construction of Iron Girders; and I do hereby de*clare the following to be a full, clear, and exact description of thesame, reference being had to the accompanying drawing and to the lettersof reference marked thereon.

My invention relates to an improvement in metallic truss frame girders,having upper and lower chords of angle iron, and my improvement consistsin the employment of packing pieces so arranged in respect to the postsand angle iron chords that the said posts and packing pieces shall serveto retain the vertical flanges of the angle iron chords in their properposition free Jfrom all liability to warp, the posts at the same timeserving as bearings for the horizontal anges of the angle iron, whilethe packing pieces, which may be varied in thickness throughout thelength of the girder, serve to impart a graduated rigidity to the same.

The object of my invention is to Jform a metallic truss frame girder,cheap and simple in construction, and extremely light in proportion toits strength.

In order to enable others to make and use my invention I will nowproceed to describe its construction and operation.

On reference to the accompanying drawing, which forms a part of thisspecification, Figure l is a side View of a portion of my improvedgirder; Fig. 2, a transverse sectional elevation on the line l, 2 Fig.1; Fig. 3, the same on the line 3-4 Fig. 1, and Fig. 4, a plan view.

Similar letters refer to similar parts throughout the several views.

The girder is composed of the cast iron posts A and A', the upper angleiron ribs B and B', the lower angle iron ribs C and C' upper packingpieces D and D', lower packing pieces E and E' and the diagonal bracesGr.

The cast iron plates are fitted snugly to the angle iron ribs, as seenin Figs. 2 and 3, and the packing pieces D and D', which eX- tendthroughout the entire length of the girder and which vary in thickness,are fitted between the diagonal braces and vertical flanges of the angleiron ribs, the diagonal braces occupying a position midway between theopposite posts of the grder when the latter is viewed transversely. Atthe top and bottom of the girder, a bolt or rivet I passes through theopposite post-s, through the vertical langes of both angle iron ribs,through the packing pieces as well as through the diagonal braces, thussecuring the whole firmly together.

In the application of angle iron to girders and other structures, it isessential that the vertical rib which has to resist the greatest strain,should be prevented from warping and buckling. This requirement is fullyprovided for in my improved girder by fitting the ends of the postssnugly to the angles formed by the two flanges of the angle iron andsecurely confining the vertical flanges of that angle iron between theposts and packing pieces by means of the bolts I. By thus confining thevertical flanges of the angle iron, it cannot become warped ordisarranged, unless the bolts I and theentire girder be broken. As thevertical pressure on the horizontal flanges of the angle iron ribs isreceived by the ends of the posts, the latter serve to maintain the saidflanges in their proper horizontal position.

One of the main advantages of my improvement is the facility with whichthe packing pieces may be made to impart a graduated rigidity to thegirder, The angle iron chords or ribs have the same thickness and depthof flanges throughout the entire length of the girder, but the packingpieces may be made of varying thickness, the thickest packing piecebeing in the middle of the girder and the thinnest packing pieces at theopopsite ends as best observed or reference to Fig. 4, in which twothicknesses of packing pieces only are shown. It will be readily seenthat for girders of greater length, three, tour, or more differentthicknesses of packing pieces may be used. The junction of the packingpieces being at a distance from the junction of the angle iron chords,the heavy costly and uncertain spliced joints which would be required inthe absence of the packing pieces, are avoided.

The posts in addition to the duty of imparting rigidity to the girderserve, with the packing pieces, to maintain the angle iron chords inthat undisturbed position which renders them most available forresisting the strains to which they are subjected, and that the packingpieces al'ord a means of graduating the rigidity of the grder as Well asof or verticals, when applied, and arranged in facilitating theconstruction of the same by respect to each other as and for the purposea simple arrangement of joints. herein set forth.

I Wish it to be understood that I do not In testimony whereof, I havesigned my 15 5 claim broadly the employment in the conname to thisspecification7 in the presence of struction of truss frame girdersfofcast iron -WO SubSCrblng Witnesses. posts combined With angle ironchords; but JN0 W MURPHY I claim as my invention and desire to sel cureby Letters Patent- I Witnesses:

10 The'combination of the Within described HENRY HowsoN,

angle iron chords, packing pieces, and posts CHARLES D. FREEMAN.

